In the News (Thu 14 Dec 17)

The CANDUreactor is a Pressurized Heavy WaterReactor developed initially in the late 1950s and 1960s by a partnership between Atomic Energy of Canada Limited (AECL), the Hydro-Electric Power Commission of Ontario (now known as Ontario Power Generation), Canadian General Electric (now known as GE Canada), as well as several private industry participants.

Where light-water reactors require the reactivity associated with enriched fuel, the DUPIC fuel cycle is possible in a CANDU due to the neutron economy which allows for the low reactivity of natural uranium and used enriched fuel.

CANDU 6 reactors have also demonstrated a superb capacity factor, averaging 88% (as low as 80% for older versions of the design).

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate (as opposed to a nuclear explosion, where the chain reaction occurs in a split second).

The concept of a natural nuclear reactor was theorized as early as 1956 by Paul Kuroda at the University of Arkansas [1].

The fraction of the reactor's fuel core replaced during refueling is typically one-fourth for a boiling-water reactor and one-third for a pressurized-water reactor.

en.wikipedia.org /wiki/Nuclear_reactor (3442 words)

CANDU reactor -(Site not responding. Last check: 2007-11-06)

The CANDUreactor is a Pressurised Heavy WaterReactor designed in the late 1950s and 1960s by a partnership between Atomic Energy of Canada Limited (AECL) and the Hydro-Electric Power Commission of Ontario (now known as Ontario Power Generation), as well as several private industry participants.

CANDU can even be operated to "burn" former nuclear weapons material (MOX fuel cycle) to a less-reactive state effectively rendering it useless for warheads while at the same time turning the relatively easily handled weapons grade material into highly radioactive waste.

One economic disadvantage of the CANDUreactor design is the initial, one-time cost of the heavy water, although this high capital-cost penalty is generally offset by the CANDUreactor's lower fuelling cost compared to other designs, since it does not require enriched uranium.

The CANDUreactor was designed by Atomic Energy Canada Limited (AECL) as an alternative to other reactor designs which use slightly enriched uranium (2-5% U-235).

The reactor, refueling machine, and fuel designs are illustrated and discussed under CANDUreactor and fuel design.

CANDUreactors differ from many other designs in that there is more extensive use of computer-based control systems including for reactor protection.

www.nucleartourist.com /type/candu.htm (643 words)

Stop CANDU Exports to Thailand(Site not responding. Last check: 2007-11-06)

First, the reactor pressure tubes are prone to rupture and to rapid deterioration, a phenomenon known as "premature aging." Because of this, CANDUreactors have to be retubed, virtually rebuilt, after 15 to 20 years of operation at a cost higher than the cost of building the reactor.

In December 1994, for the first time in the CANDUreactor history, operators at Ontario Hydro's Pickering plant had to use the emergency coolant system to avoid a meltdown, when a valve failure caused 140 tonnes of heavy water to be dumped out of the reactor.

One of the CANDUreactor byproducts is tritium, a radioactive form of hydrogen, produced when water is exposed to neutron radiation in the reactor core.

By definition, a major reactor accident would lead to the severe overheating, and subsequent melting, of the nuclear fuel, which would give rise to a substantial quantity of radioactive material escaping, after breaching several formidable barriers, into the environment.

It is generally agreed that the greatest threat to health in the event of a major reactor accident is the considerable quantity of the radio-isotope iodine-131 (with a specific activity of 120,000 curies/gram, and a half-life of 8.

When we talk about the safety of a nuclear reactor, we are referring essentially to how effectively the fantastic amount of radioactivity contained in the reactor core can be prevented from escaping into the ground and atmosphere in the event of major malfunctions.

CANDU technology transfer (unlike the transfer of other reactor designs, which are controlled by large, integrated private sector corporations such as GE, Westinghouse or Siemens) is in the hands of a number of private sector component manufacturers as well as AECL.

The licensing fee was to be $5 million per reactor for Romania's first four reactors, decreasing to $2 million per reactor thereafter for the last of a total of 16 reactors that were anticipated.

The 1 MW reactor, known as TR-1 (Turkish Reactor-1) went critical in 1962 and was reportedly shut down in September 1977, but was upgraded to 5 MW by Belgonucleare in 1980.

The study estimated the time for going through the reactor vessel to be 1 to 1 and 1/2 hours and through the base slab to be an additional 13 to 28 hours.

CANDU was a pressure tube reactor, where the neutron moderator is separate from the reactor coolant, which causes the positive void coefficient.

The reactor began shutting itself down within seconds, but as the control room operator shouted for help and began to frantically hit buttons, trying to restore pressure, something else went terribly wrong: a pipe on the other side of the rogue valve burst, and the water pressure started to drop again.

Of all commercial reactors, the CANDU design produces the most plutonium per unit of energy, and is the most difficult to safeguard.

It is a sobering thought that the plutonium produced in a CANDUreactor can be used for bombs by any regime in any of our client countries, at any time in the next twenty thousand years Ð long after the reactor that produced the plutonium has been shut down, decommissioned and forgotten.

The 1 MW reactor, known as TR-1 (Turkish Reactor-1) went critical in 1962 and was reportedly shut down in September 1977, but was upgraded to 5 MW by Belgonucleare in 1980.{227} The upgraded 5 MW reactor, known as TR-2 first went critical in December 1981.

This website, established in April 1996, is an unofficial and privately-maintained list of Frequently-Asked Questions (FAQ's) regarding CANDUreactors and nuclear power generation in Canada.

The CANDU fuel bundle pictured weighs 23 kg, is about the size of a fire log, and produces enough electricity to power 100 average Canadian homes for a year.

He is a reactor physicist at Atomic Energy of Canada Ltd.'s (AECL) Chalk River Laboratories, a Past President of the Canadian Nuclear Society (CNS) and a member of the Board of Directors of the American Nuclear Society (ANS).

CANDUREACTOR: The spatial kinetic behavior of the CANDUreactor is approximated by 14 coupled micro-reactors.

The Reactor Regulating System (RRS) model includes liquid zone controllers for bulk power and flux-tilt controls, with adjuster rods and/or absorber rods movement being regulated by the specialized CANDU "reactivity diagram".

If you are interested in other reactor types other than PHWR, PWR, BWR, such as high temperature gas cooled reactor, etc., we are in the process of developing and validating other reactor type algorithms.